Template-free synthesis of porous graphitic carbon nitride microspheres for enhanced photocatalytic hydrogen generation with high stability

Graphitic carbon nitride microsphere photocatalysts were prepared through a template-free solvothermal approach with post-heating treatment. Structural characterization results reveal that the as-prepared sample has the same composition as bulk g-C₃N₄, but appears as hierarchical microspheres with nanoporous surfaces. Comparing to the bulk g-C₃N₄, these porous microspheres exhibit narrowed bandgap and lower resistance, which allows more effective visible-light harvesting and more efficient transport and separation of photogenerated charge carriers. Consequently, we observed high rate of photocatalytic H₂ production and stronger photocurrent responses under visible light irradiation. Further, the long-term photocatalytic test proved high stability of the prepared nanoporous microsphere for H₂ generation.